Ammonia gas sensor based on pentacene organic field-effect transistor

Ammonia (NH3) sensors based on bottom contact organic field-effect transistors (OFETs) were created using pentacene as an active layer and polymerthylmethacrylate (PMMA) as an insulator. The OFET sensors exhibited a change in the electric characteristic such as the threshold voltage, the saturation current, and the field-effect charge carrier mobility when the sensors were exposed to different NH3 concentrations. Meanwhile, the favorable and rapid NH3 response characteristics of the OFET sensors were observed from the change in the drain-source current as a function of time, when the sensors were exposed to various cycles of exposure/evacuation of different NH3 concentrations ranging from 10 to 100 ppm. Moreover, the environmental stability of the OFET sensors to constantly detect the NH3 gas in air was studied by storing the sensors in air for 30 days.